Streamed media, such as video, is typically delivered from a source, e.g., a media server, to a client as a substantially continuous stream of data at a substantially constant bitrate, the media bitrate. If the media stream is delivered via a RAN, i.e., the client is a User Equipment (UE), this may result in an inefficient utilization of the air interface since radio resources which are allocated to the UE have to support link bitrates exceeding the media bitrate.
According to the 3rd Generation partnership Project (3GPP), a number of communication states are defined, also referred to as Radio Resource Control (RRC) states, in which the UE may reside. In general, communication states which provide the UE with a higher bitrate are more resource consuming, and vice versa. In addition to an inefficient utilization of the air interface, the described approach has a negative impact on UE battery lifetime. In the Universal Mobile Telecommunications System (UMTS), e.g., the states in RRC connected mode are, in order of decreasing resource consumption, CELL_DCH (Dedicated Channel), CELL_FACH (Forward Access Channel), CELL_PCH (Cell Paging Channel) and URA_PCH (URA Paging Channel).
In order to utilize air interface resource more efficiently and to reduce power consumption on the UE side, streamed media may be reshaped into sequences of bursts and silent periods, such that bursts of data are transmitted to the client at a bitrate which is substantially larger than the media bitrate, and preferably utilizing the supported link bitrate to as large extent as possible, alternated with silent periods during which a transition of the UE to a less resource consuming communication state may be performed. The reshaping may be performed by the media server providing the media stream, a proxy, a node of the RAN, or any other network node involved in delivering streaming sessions to the RAN.
The transition from a higher communication state, e.g., CELL_DCH, to less resource consuming communication states, e.g., CELL_FACH or CELL_PCH, is effected by a control node of the RAN and is triggered by inactivity timers which are configured by the operator, with a typical duration of about a few second to ten seconds. The control node of the RAN may, e.g., be a Radio Network Controller (RNC), an eNodeB, or the like.
In order to further increase radio efficiency and reduce UE power consumption, it has been proposed to provide the control node of the RAN with information pertaining to a pattern of bursts and silent periods transmitted to the RAN, so as to enable switching to a less resource consuming communication state immediately after transmission of a burst has terminated, instead of waiting for an inactivity timer to expire. This may be achieved by providing the control node with information about a burst pattern to be transmitted to the RAN. Alternatively, the control node may be provided with an end-of-burst (EoB) indication, in response to which a transition to a less resource consuming communication state may be initiated.
However, the usefulness of reshaping media streams into bursts, and providing the control node of the RAN with information about a burst pattern to be transmitted or an EoB indication, is limited by the fact that modern UEs, such as smartphones, typically maintain several communication sessions in parallel, i.e., simultaneously. These sessions may, e.g., be associated with different applications which are executed in parallel, such as an email application, a video player, a chat application, and the like. In this case, the UE may be prevented from switching to a less resource consuming communication state during a silent period of the media stream, requested by the video player, because another application is receiving data at the same time, e.g., if the email application is syncing with a server.